There are several people mentioned in Jude verse 11 who we can read about in the Old Testament. First we have Cain. You can read his story in Genesis 4. Cain was born to Adam and Eve, along with his brother Abel. Cain offered “some” of his harvest to the Lord, while Abel gave God the “first fruits.” Because of their heart posture, God received Abel’s offering and not Cain's. This made Cain jealous and angry, and he killed his own brother. 

Jesus gave us freedom from sin, and the power to obey God. When we live this way, we show our love for Jesus. This relationship between obedience and love is vital. If you have only ever obeyed (your parents, your boss, your teachers) out of fear, or you have only obeyed (while they were watching) for approval, that is living out of instinct.  Obedience must come from love.

We want to be people who live and function under the inspiration of the Holy Spirit. Inspiration and instinct, however, can be difficult to distinguish between. Someone who has learned to survive on instinct can be really good at saying the right thing at the right time; they seem inspired. There is really only one way to tell for sure whether an individual is acting off of instinct or inspiration: look at their lives.

In Genesis 19, you can read the account of Sodom and Gomorrah. The cities had become so wicked and sexually immoral that God was going to destroy them. Even as Angels were sent to rescue Abraham’s nephew, Lot, the city showed its true colors. The men of the city beat on the doors of Lot’s house, demanding to sexually assault the visitors. The Angels escaped with Lot and his family.

The behavior Jude is highlighting here is sexual immorality and selfishness. The people who had wormed their way into the church Jude was concerned about were teaching that it was okay to indulge in sin because Jesus had paid for it; they were corrupting the teaching of grace. Like the fallen angels who left their heavenly posts, they were abandoning the high calling of a life faithful to Jesus, filled by His Spirit, for a selfish and wicked existence.